Instruction manual

6. MODBUS COMMUNICATION PROTOCOL
IMR01H02-E3
51
6.6.3 Diagnostics (loopback test) [08H]
The master’s query message will be returned as the response message from the slave. This function
checks the communication system between the master and slave.
Example: Loopback test for slave address 1
Query message
Slave address 01H
Function code 08H
Test code High 00H
Low 00H
Data High 1FH
Low 34H
CRC-16 High E9H
Low ECH
Normal response message
Slave address 01H
Function code 08H
Test code High 00H
Low 00H
Data High 1FH
Low 34H
CRC-16 High E9H
Low ECH
Error response message
Slave address 01H
80H + Function code 88H
Error code 03H
CRC-16 High 06H
Low 01H
Test code must be set to 00.
Contents will be the same as query message data.
Any pertinent data